Lecture Notes: Reflection and Lenses

Introduction

• Introduction to visible light and reflection.
• Discussion on how images are formed on mirrors.

Reflection

• Reflection: Bouncing of light rays when they hit a surface.
• Specular Reflection: Occurs on smooth surfaces like plain mirrors. Angle of incidence = angle of reflection.
• Diffuse Reflection: Occurs on rough surfaces and illuminates shaded areas like rocks and buildings.

Law of Reflection

• Angle of incidence = Angle of reflection.
• Defined by the normal line, incident ray, and reflected ray.

Image Characteristics

• Magnification: Ratio of image dimensions to object dimensions.
• Real Image: Formed when rays converge.
• Virtual Image: Formed when rays appear to diverge.
• Orientation: Upright or inverted.
• Location: Depends on object's location.
• Size: Can be larger, smaller, or the same.

Plane Mirrors

• Virtual Image: Formed from behind the mirror.
• Orientation: Upright and laterally inverted.
• Size and Magnification: Image size = object size; magnification = 1.
• Lateral Inversion: Left side of the object appears on the right side of the image.

Curved Mirrors

• Types: Concave and convex.
• Elements:
  • Principal Axis
  • Center of Curvature (C)
  • Vertex (A)
  • Focal Point (F)

Concave Mirrors

• Image characteristics depend on the object's location:
  • Beyond Center of Curvature: Inverted, reduced size, real image.
  • At Center of Curvature: Inverted, equal size, real image.
  • Between Center and Focal Point: Inverted, enlarged, real image.
  • At Focal Point: No image formed.
  • Beyond Focal Point: Upright, magnified, virtual image.

Convex Mirrors

• Always produce a virtual, upright, and smaller image.

Mirror Equation

• ( \frac{1}{F} = \frac{1}{P} + \frac{1}{Q} )
  • F: Focal length
  • P: Distance of the object from the mirror
  • Q: Distance of the image from the mirror
• Magnification: ( \frac{h'}{h} = -\frac{Q}{P} )

Sample Problem

• Calculation of image distance and size using the mirror equation and magnification equation.

Lenses

• Lens: Transparent material that refracts light to form images.
• Convex Lens: Converges light rays.
• Concave Lens: Diverges light rays.

Convex Lenses

• Image characteristics depend on object's location:
  • Beyond 2F Point: Inverted, smaller, real image.
  • At 2F Point: Inverted, equal size, real image.
  • In Front of 2F Point: Inverted, enlarged, real image.
  • At Focal Point: No image formed.
  • In Front of Focal Point: Upright, enlarged, virtual image.

Concave Lenses

• Always produce a smaller, upright, virtual image.

Lens Equation

• Same as mirror equation; use signs for focal lengths and image distances based on lens type.

Recap

• Law of reflection and characteristics of images in mirrors and lenses.
• Differences between concave/convex mirrors and lenses.

Conclusion

• Upcoming discussion on uses of mirrors and lenses in optical devices.
• Encouragement to subscribe for more content.